1. Field of the Invention
This invention relates to lubricants suitable for use in food processing machinery, comprising a food grade lubricating base oil and a combination of food grade additives to impact good resistance to wear, oxidation and rust and to exhibit improved resistance to sludging in service while retaining the ability to emulsify and/or disperse aqueous and other contaminants.
2. Description of the Related Art
Food grade lubricant systems for use in food processing machinery such as can seamer equipment, conveyor belts, grinders, heaters, ovens, mixers, etc., have long been known and formulated.
U.S. Pat. No. 4,753,742 describes a food grade lubricant comprising food grade mineral oil and 1% to 90% lecithin as well as non-ionic surface active emulsifying agents and vegetable oils.
U.S. Pat. No. 4,506,533 describes a method for drawing and ironing aluminum containers and a lubricant for use in the method, the lubricant comprising unemulsified peanut oil and/or certain oleic acid esters of aliphatic polyhydric alcohols, e.g., sorbitol trioleate.
U.S. Pat. No. 4,445,813 describes a method for forming seamless containers using a lubricant consisting essentially of a fatty acid ester of a mono or poly-hydric alcohol.
U.S. Pat. No. 4,767,554 describes a concentrate useful for preparing oil-in-water emulsion lubricants used in drawing and ironing ferrous and non-ferrous metals comprising 60-90 wt % carboxylic acid ester from the group consisting of dibasic acids having at least 70 wt % of the carboxylic acid groups esterified with C.sub.4 -C.sub.30 monohydric alcohols and C.sub.8 -C.sub.22 mono carboxylic acid ester of a poly-hydric alcohol, 0.5-30 wt % water-in-oil emulsifying agent, 2-4 wt % polyglycol co-emulsifier, 0.5-2 wt % phosphate corrosion inhibitor, 0.2-1 wt % copper corrosion inhibitor and 0-10 wt % thickener.
U.S. Pat. No. 5,102,567 describes a food grade lubricating oil which provides superior oxidation, thermal and hydrolytic stability properties and comprises a food grade lubricating oil base stock and a combination of anti oxidants comprising a mixture of food grade phenolic anti oxidants and food grade aminic anti oxidants, each anti oxidant being present in an effective amount of less than about 1.0 wt %. Other additives which may be present include food grade anti wear additives, anti rust additives. Rust inhibitors can be of the ionic or non-ionic type. Ionic types include phosphoric acid ester compounds with amines. Non-ionic types include fatty acids and their esters formed from polyhydric alcohols or polyalkylene glycols, or ethers from fatty alcohols, sorbitan and sorbitan esters alkoxylated with alkylene oxides.
U.S. Pat. No. 5,151,205 describes a lubricant comprising polyalphaolefin base oil and 2-4 wt % polybutene tackifiers.